html, body {
    margin: 0px;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

nav {
    position: fixed;
    top: 0px;
    left: 0px;
}

nav button {
    padding: 5px 20px;
    margin: 5px;
}

canvas {
   width: 100%;
   height: 100%;
}